The time prisoners spend on death row has nearly doubled during the past two decades. Legal experts predict it will rise further as states review execution procedures and prisoners pursue lengthy appeals. Waits rose from seven years in 1986 to 12 years in 2006, the latest Justice Department statistics show. In all five states with the most prisoners on death row — California, Florida, Texas, Pennsylvania and Alabama — offenders spend more time in prison than they did four years ago, a USA TODAY survey of state records through 2007 found.

In California, wait times average nearly 20 years, a state commission report in June says. It costs about $90,000 more per year to house a death row inmate than other inmates.

In April, the U.S. Supreme Court upheld Kentucky's lethal injection method, ending an informal halt to executions nationwide for seven months. Of the 10 states with the most prisoners on death row, five launched their own reviews of lethal injection procedures in the past two years. Those resulted in suspensions or delays in executions.